最短路径 java代码
时间: 2023-09-15 11:23:01 浏览: 41
以下是使用 Dijkstra 算法求最短路径的 Java 代码示例:
```java
import java.util.*;
public class DijkstraAlgorithm {
private int dist[];
private Set<Integer> settled;
private PriorityQueue<Node> pq;
private int V;
List<List<Node> > adj;
public DijkstraAlgorithm(int V) {
this.V = V;
dist = new int[V];
settled = new HashSet<Integer>();
pq = new PriorityQueue<Node>(V, new Node());
}
public void dijkstra(List<List<Node> > adj, int src) {
this.adj = adj;
for (int i = 0; i < V; i++)
dist[i] = Integer.MAX_VALUE;
pq.add(new Node(src, 0));
dist[src] = 0;
while (settled.size() != V) {
int u = pq.remove().node;
settled.add(u);
e_Neighbours(u);
}
}
private void e_Neighbours(int u) {
int edgeDistance = -1;
int newDistance = -1;
for (int i = 0; i < adj.get(u).size(); i++) {
Node v = adj.get(u).get(i);
if (!settled.contains(v.node)) {
edgeDistance = v.cost;
newDistance = dist[u] + edgeDistance;
if (newDistance < dist[v.node])
dist[v.node] = newDistance;
pq.add(new Node(v.node, dist[v.node]));
}
}
}
public static void main(String[] args) {
int V = 6;
int source = 0;
List<List<Node> > adj = new ArrayList<List<Node> >();
for (int i = 0; i < V; i++) {
List<Node> item = new ArrayList<Node>();
adj.add(item);
}
adj.get(0).add(new Node(1, 5));
adj.get(0).add(new Node(2, 3));
adj.get(1).add(new Node(3, 6));
adj.get(1).add(new Node(2, 2));
adj.get(2).add(new Node(4, 4));
adj.get(2).add(new Node(5, 2));
adj.get(2).add(new Node(3, 7));
adj.get(3).add(new Node(5, 1));
adj.get(3).add(new Node(4, -1));
adj.get(4).add(new Node(5, -2));
DijkstraAlgorithm dpq = new DijkstraAlgorithm(V);
dpq.dijkstra(adj, source);
System.out.println("The shortest distance from source node " + source + " to all other nodes:");
for (int i = 0; i < dpq.dist.length; i++)
System.out.println("Node " + i + " - Distance: " + dpq.dist[i]);
}
}
class Node implements Comparator<Node> {
public int node;
public int cost;
public Node() {}
public Node(int node, int cost) {
this.node = node;
this.cost = cost;
}
@Override
public int compare(Node node1, Node node2) {
if (node1.cost < node2.cost)
return -1;
if (node1.cost > node2.cost)
return 1;
return 0;
}
}
```
这是一个使用 Dijkstra 算法在带权图中求最短路径的 Java 代码示例。